Benthic+Zone

Benthic Zone Walter Crespo could you add some references?


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Introduction to the Benthic Zone:

The benthic zone begins at the edge of the sea at the intertidal zone, extends out along the continental shelf, and continues down the continental slope to the abyssal plain, thousands of meters below sea level. It includes the entire seabed, rising along the mid-ocean ridges where new sea floor is continually being made, and dives down into the deep ocean trenches. The habitats of the benthic zone vary widely depending on how far below the surface the bottom lies. Just beyond the intertidal zone, the shallow water receives ample sunlight and oxygen. Continuing down along the continental slope, the environment becomes increasingly dark and cold, and the pressure increases. A remarkable variety of organisms live in these different habitats, each with specialized adaptations reflecting the conditions of their environment.

[|__http://www.bbc.co.uk/nature/habitats/Benthic_zone__] //Click the link above to see videos of the Benthic Zone//

Flora: Most of the plants found there are algae and seagrasses, which are also called phytobenthos. Phytobenthos will occur more often in the superior levels of the benthic zone, since they depend on the sun for photosynthesis. There are many categories of these type of organisms:

Microphytobenthos
These organisms are microscopic, unicellular or filamentous. Microphytobenthos normally live in sedimentary shores, according to Wehr and Sheath in the book "Freshwater Algae of North America: Ecology and Classification."

Common microphytobenthos species living on the bottom of North-American rivers, lakes and sea coasts include:


 * Navicula
 * Gyrosigma
 * Nitzchia
 * Diploneis
 * Plagiotropis
 * Amphora
 * Fallacia
 * Cylindrotheca
 * Euglena
 * Staurophora



Macrophytobenthos
According to the 4Seas Project, macrophytobenthos include green algae (Chlorophyceae), brown algae (Phaeophyceae), red algae (Rhodophyceae), and plants of the family Potamogetonaceae.

Green Algae
These algae or seaweeds are rich in chlorophyll that gives their characteristic color. They can live in the benthic zone as individuals or colonies. These are common species:


 * Zostera marina (eelgrass)
 * Ulva lactuca (sea lettuce)
 * Cladophora rupestris
 * Codium fragile (spongeweed)
 * Codium tomentosum
 * Monostroma grevillei
 * Spongomorpha aeruginosa

Brown Algae
The dominance of the pigment xanthophyll determines the brown color of these algae. According to Michael Guiry&rsquo;s Seaweed Site, there are about 1800 species of brown algae, most living in marine environments. Some examples:


 * Fucus vesiculosus (bladderwrack)
 * Ascophyllum nodosum (Norwegian kelp)
 * Sargassum sp
 * Macrocystis pyrifera (giant kelp)



Red Algae
There are 6000 described species of red algae, as stated in Michael Guiry&rsquo;s Seaweed Site. The red color results from the pigments phycoerythrin and phycocyanin. Examples include:


 * Atractophora hypnoides
 * Gelidiella calcicola
 * Lemanea fluviatilis
 * Lemanea fucina
 * Palmaria palmata (dulse)
 * Schmitzia hiscockiana
 * Chondrus crispus (Irish moss)
 * Mastocarpus stellatus (false Irish moss)
 * Ceramium



Potamogetonaceae
Potamogeton, the only family of macrophytobenthos able to produce flowers and fruit, is the largest genus. Some species:


 * Zannichellia palustris (horned pondweed)
 * Potamogeton alpinus
 * Potamogeton pectinatus (fennel pondweed)
 * Lepilaena marina
 * Lepilaena preissii
 * Althenia
 * Groenlandia
 * StF



Fauna: The organisms that live in the benthic zone are collectively called "benthos." They include crustaceans, mollusks, worms, fish, and any other type of organism that makes its home on or in the seabed.

The majority of benthos are scavengers or detritus feeders that eat decomposing organic matter. Much of the food supply in the benthic zone is in the form of detritus small particles of decaying organic matter that slowly descend through the water column and accumulate on the ocean floor. Benthos in the intertidal zone include sea stars, barnacles, mussels, sea anemones, sea urchins, snails, and other creatures that attach themselves to the rocky substrate or burrow in the sand. Benthos in deeper zones include fish, crustaceans and tube worms.



Benthic fish, also known as groundfish, are those that stay on or very near the sea bottom, whether in shallow or deep water. Unlike fish that spend their time swimming, benthic fish are very dense and have negative buoyancy, allowing them to effortlessly lie on the bottom or bury themselves. Other adaptations commonly seen in benthic fish include the lack of a swim bladder and a flattened body shape. They are predominantly bottom feeders that eat detritus, or ambush predators that lie in wait for their prey to come within striking distance.



Temperature: Temperature in the benthic zone ranges from warmer temperatures at shallow depths because of close proximity to the water surface, but may drop to 2 °C to 3 °C at the most extreme depths of the abyssal zone. At such cold temperatures, abundance of life is quite low and organisms move at a very slow pace. Warmer waters at shallower depths provide much more energy and can host more complex systems

Example of the expansive reach of the Benthic zone pertaining to the varied temperatures. Human Impact and Interactions: Humans interact with the benthic zone through food such as shrimp.

In the deepest part of the ocean, another way humans interact with the benthic zone is through exploration through remote-control submarines. Mapping and observing through remote controlled submarines. The effect of exploration through remote-control submarines is gaining knowledge of organisms we cannot get to.

A third way humans interact with the benthic zone would be through scuba-diving or via submarines along the ocean floor where they can view beautiful coral reefs and sealife with their own eyes.

Impacts of human activity on benthic zones would be through Drilling for oil on the ocean floor, Mining for gold and other valuable ores,Fishing for sea life such as shrimp and other fish, and Pollution.

Other than that the biggest and probably only threat are humans, but the bethic zone is so vast and deep that humans have little affect on it.